Process of unhairing hides and skins



I Patented Apr. 1930 UNITED STATES PATENT OFFICE.

HARRY M. ULLMANN AND EDWIN R. THEIS, F BETHLEHEM, PENNSYLVANIA rnocnssor UNHAIRING HInns AND SKINS No Drawing.

This invention relates to a process of unhairing hides and skinsinvolving the use of the pancreatic enzymes. For brevity in thefollowing description only hides will be referred to, it beingunderstood that animal skins generally are meant unless otherwiseindicated. Theunhairing of hides, i. e.,' the skins of large full grownanimals, such as steer hides, is the principal application of theinvention, Also for the sake of brevity only stance, it has beenproposed to subject hides to be unhaired to a preliminary swelling in anacid or alkaline solution and thereafter 5 tov subject the hides to theaction of pancreatin until unhairing occurs, that is, until the haircanbe removed, for instance bysliding a finger over the hide. Thistreatment, however, works an undesirable degenerative so and destructiveaction upon the hide, in-

cluding digestion of the derma.

Our process is, in a sense, a modification .of the so-called limingprocess. It is not designed to and does not eliminate liming but has theadvantage that it greatly shortens the customary lime treatment. In thecustomary liming process cured hides are first soaked in-water for about24 hours toremove salt and are then put into a solution of lime forabout 120 hours, more or less, depending upon the kind and condition ofthe hide and other factors after which the hair may be removed in theknown way. It will be understood that our process as described .isadapted to the treatment ofcured or salted hides, although it readilymay be modified and adapted to the treatment of fresh or uncured hides.

Accordingto the process of our invention,

the cured hides are not subjected to any pre- Application filed December26, 1928. Serial No. 328,619.

liminary swelling in acid or alkali nor to a preliminary and independentsoaking as in the Well-knownliming process but the pancreatin is addeddirectly to the Water used for. soaking the hides. Thus it may beconsidered that the customary soaking is replaced by a treatment withpancreatin or more logically that the treatment with pancreatin issuperimposed upon or combined with the customary soaking, It isdesirable, although not essential, that the pancreatin beadded at thebeginning of the soaking. The soaking in the presence of pancreatin iscontinued for about the customary length of time, say 20 hours, (thisperiod of time may vary with the'condition, cure and 'kind of hide, thetemperature of operation, the concentration and activity of thepancreatin in the bath, etc.) and the hide is then trans ferred to thecustomaryliining liquor where it is left for only a comparatively shorttime, say 20 hours, after which it is ready for the usual mechanicaltreatment for removing the loosened hair. It is noted'that the hide isnot left in the pancreatin-containing soaking bath until unhairingoccurs, i. e., until the hair may be removed by sliding a finger overthe hide. Indeed'the hair should be still tight at the end of thesoaking treatment. Due to the great variation in hides, it is impossibleto specify precise conditions for the treatment of all hides. Weprefer-for the sake of economy to use a dilute solution of pancreatinfor the combined pancreatin and soaking treatment, for example -.02% to04% of pancreatin based on the weight of the soaking Water or solution.Higher concentrations of pancreatin up to say 0.1% may be usedwith ashortening of, the treatment. The concentration of pancreatin in thesoaking solution may vary from a minimum effective quantity, the lowerlimit apparently being in the neighborhood of .0l% up to that quantitywhich in a given time will deleteriously aifect the hide. F or example,a 1% solution acting upon steer hide at. 70 F. for 20 hour-s ordinarilydetrimentally affects the hide. f

The temperature, about 60 F. to F., and other conditions observed in themodified soaking and liming operations are the same as those used in thecustomary soaking and liming operations, the only variations being thosereferred to above, i. e., that the soakinilwater has pancreatin added toit and the soa 'ng operation is limited, if necessary, to avoid detrmental action upon the hide, it

(being unnecessary to'loosen the hair by the action of the pancreatin inthe soaking bath, and the liming treatment is limited to a timesufiicient to loosen the hairthe usual effect of liming. o

The treatment described does not result in any appreciable degenerationof the derma of the hide. Net gains in hidedue to hydration and theamount andiqnality of the finished leather are normal .as-compared withthe product obtained by the known soaking and liming process.

We claim: 1. Process of unhairing hides which comprises soaking thehidesinwatercontainmg 'pancreatin and thereafter liming the soaked hide.

2. Process of unhairing hides which comprises contacting the hides witha solution of pancreatin for a substantial period of time insufiicientto produce unhairing and thereaftei' treating the hides with a solutionof lime until the hair is loosened.

3-. Process of unhairing hides which comprises soaking cured hides inthe presence of pancreatin in quantity amounting to from about 02% to0.1% of the soaking liquid for a substantial period short of timesuflicient to produce unhairing and thereafter subjecting the hides to ashort liming treatment.

4. Process of unhairing hides which com- I prises soaking cured hides inthe presence of pancreatin in quantity amounting to from .02% to 04% ofthe soaking liquidfor about 20 hours at a temperature of from Flto F.and'thereafter liming the hides for about 20 hours.

In testimony whereof, we aflix our tures.

. signa- HARRY M. ULLMANN.

EDWIN RTHEIS.

